Scald's burn chance can help patch up Tentacruel's poor Defense while also providing it with a reliable STAB attack. Toxic Spikes is useful for the passive damage it inflicts on grounded Pokemon. It's also the main reason why you would use Tentacruel over other Rapid Spin users. Toxic is a nice alternative, as it can inflict poison on Flying-type or Pokemon with Levitate, which are not affected by Toxic Spikes. Knock Off removes items from opposing Pokemon, which helps greatly when facing stall-based teams. Rapid Spin is obviously the most important move, and allows Tentacruel to support its team by removing entry hazards.